Absorbent article with core-to-backsheet glue pattern comprising two glues

ABSTRACT

An absorbent article comprises a topsheet on the wearer-facing side, a backsheet on the garment-facing side, and an absorbent core positioned between the topsheet and the backsheet. The absorbent core comprises an absorbent material comprising a superabsorbent polymer, a core wrap enclosing the absorbent material, and a first channel disposed on one side of the longitudinal axis and a second channel disposed on the other side of the longitudinal axis.

FIELD OF THE INVENTION

The invention relates to personal hygiene absorbent articles of the typeworn in the crotch region of an individual to absorb body exudates. Theabsorbent articles may in particular be baby and toddler diapers(including training pants), feminine sanitary pads and/or adultincontinence articles. The present invention relates more particularlythe core-to-backsheet glue pattern of these articles.

BACKGROUND OF THE INVENTION

Absorbent articles for personal hygiene of the type indicated above aredesigned to absorb and contain body exudates, in particular largequantity of urine. These absorbent articles comprise several layersproviding different functions, for example a wearer-facing topsheet, agarment-facing backsheet and in-between an absorbent core, among otherlayers. The function of the absorbent core is typically to absorb andretain the exudates for a prolonged amount of time, minimize re-wet tokeep the wearer dry and avoid soiling of clothes or bed sheets.

The majority of currently marketed absorbent articles comprise asabsorbent material a blend of comminuted wood pulp with superabsorbentpolymers (SAP) in particulate form, also called absorbent gellingmaterials (AGM), see for example U.S. Pat. No. 5,151,092 (Buell). Coreshaving an absorbent material consisting essentially of SAP (so called“airfelt-free” cores) have also been proposed, see for exampleWO95/11652 (Tanzer), U.S. Pat. No. 6,790,798 (Suzuki), WO2008/155699(Hundorf), or WO2012/052172 (Van Malderen). Absorbent cores with slitsor grooves have also been proposed, typically to increase the fluidacquisition properties of the core or to act as a folding guide.WO2012/170778 (Rosati et al., see also WO2012/170779, WO2012/170781 andWO2012/170808) discloses absorbent structures that comprisesuperabsorbent polymers, optionally a cellulosic material, and at leasta pair of substantially longitudinally extending channels.

The various components of an article are typically attached to anotherso that they stay in place before and during usage. Typical attachmentmeans are gluing, heat and/or pressure bonding, ultrasonic bonding. Theattachment means will be chosen by the manufacturer to balance costs ofthe equipments, cost of the glue material and performance required.Absorbent cores are typically attached to the backsheet by gluing, inparticular by spraying the whole of the backsheet with a discontinuousglue layer before attaching both components together.

Alternative core-to-backsheet gluing patterns have been proposed.WO2012/170341A1 (Hippe) discloses a diaper having a reducedcore-to-backsheet gluing pattern. In Hippe, the absorbent core isattached to the backsheet only in certain, limited areas. As aconsequence, the formation of buckles and wrinkles in the backsheet, aswell as the see-through of urine stains from the absorbent core throughthe backsheet can be reduced.

The present invention is directed to an improved core-to-backsheetgluing pattern, as will be further disclosed in the followingspecification.

SUMMARY OF THE INVENTION

The present invention is directed to absorbent articles comprising atopsheet on the wearer-facing side, a backsheet on the garment-facingside and an absorbent core between the topsheet and the backsheet. Theabsorbent core comprises an absorbent material comprising asuperabsorbent polymer, in particular superabsorbent particles, a corewrap enclosing the absorbent material, and a first channel disposed onone side of the longitudinal axis and a second channel disposed on theother side of the longitudinal axis.

In short, the inventors have found that it is beneficial that suchabsorbent cores comprising channels should be attached to the backsheetby a first glue and a second glue, each glue having a glue applicationarea and a glue application pattern. The first glue area is at leastpartially present between the channels whereas the second glue has asecond glue application area at least partially outside the area betweenthe channels. The first channel and the second channel are at leastpartially not attached by the first glue and second glue, or otherwise,to the backsheet. The first glue has a different application patternthan the second glue. Advantageously, the absorbent core and thebacksheet may only be attached by first glue and the second glue.

The inventors have surprisingly found that during the article makingprocess, shearing forces on the backsheet or the core can concentratealong the glue edge of the second glue and rupture the backsheetsubstrate. The inventors have found that in presence of the first glue,the forces over the backsheet substrate are better distributed,improving not only the anchoring of the core but also preventingfailures or fatigue on the backsheet during the making or wear of theabsorbent article.

The inventors have also found that it can be beneficial to havedifferent glue properties between the first and the second glue.

Further, advantageous but non-limiting features of the inventions arenow briefly indicated in the rest of this summary. The glue pattern ofthe invention may be particularly useful for absorbent articlescomprising relatively high amount of SAP. The channels may be inparticular areas substantially free of absorbent material and which aresurrounded by absorbent material. The top layer of the core wrap can bebonded to the bottom layer of the core through the channel areas. Thefirst channel and the second channel may be longitudinally extending andhave a length as projected on the longitudinal axis which is at least25% of the length of the absorbent core.

The first glue, which is at least partially applied between thechannels, advantageously has a first application pattern which iscontinuous. By “continuous” it is meant the glue forms a uniform layeror coating that covers substantially the whole surface of the area onwhich it is applied. Continuous pattern can be typically obtained bydirect application of the glue on the substrate, such as by slot coatingor printing of the glue. “Discontinuous” refers on the other hand to aglue pattern which does not form a continuous layer on the applicationarea. A discontinuous pattern may for example comprise glue filaments,fibers or the like creating a more or less regular glue web withrelatively large areas which are not covered by the glue between theglue filaments or fibers. Discontinuous areas are typically obtained bynon-contact application method such as spraying of the glue.

The second glue application pattern may be advantageously discontinuous.For example it may comprise one and typically a plurality of largeswirls, mini swirls or random patterns. The second glue pattern mayadvantageously be used to cover large areas of the core-to-backsheetinterface as it typically requires less glue material per unit ofsurface. The second glue application area may thus be larger than thefirst glue application area, in particular the second glue area may beat least 3 times larger, or at least 5 times larger, than the first gluearea.

The second glue application area may, at least portion-wise, extendsubstantially along the full length of the absorbent core. In particularthere may be a first longitudinally extending portion on one side of thelongitudinal axis and a second longitudinally extending portion on theother side of the longitudinal axis. This provides for a secureattachment of the absorbent core along its full length. The second glueapplication area may further more extend at least portion-wise along thefull length of the backsheet, thus beyond the front and back edges ofthe core. This may be desirable for providing further attachment of thebacksheet with other components of the article in particular thetopsheet. The second glue application area may be also relatively largein the region of the front edge and the back edge of the core to providefor a stronger core-backsheet attachment in these areas, in particularto attach securely the corners of the core to the backsheet.

The present invention is also directed to a process for making anabsorbent article according to the invention. In particular, suchprocess comprises the following steps for attaching the absorbent coreto the backsheet:

-   -   applying a first glue on the backsheet or the absorbent core on        the first glue application area according to the first pattern,        which may in particular be continuous;    -   applying a second glue on the backsheet or the absorbent core on        the second glue application area according to the second        pattern, which may in particular be discontinuous; and then    -   bringing the core wrap and the absorbent core in contact so that        they are attached by the first glue and second glue.

As indicated previously, the first glue may be applied by a contactapplicator, such as a slot-coater, and the second glue may be applied bya non-contact applicator, typically a glue spray nozzle providing atleast one and typically a plurality of large swirls, mini swirls orrandom glue patterns. The second glue may be in particular applied by aplurality of nozzles disposed in parallel, wherein for each article, atleast some of the nozzles are turned on and off to provide a second glueapplication pattern comprising longitudinally extending second glueportion of different lengths (intermittent applications of the glue).This can allow reducing the consumption of the second glue by applyingthe second glue only in the desired areas, in particular wherein thesecond glue application area generally defines a roman II numeral shape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a backsheet with a glue pattern according to the invention,with the outline of the absorbent core and its channels shown in dottedlines, the rest of the article being omitted for readability;

FIG. 2 shows a schematic exploded view of some of the main components ofan absorbent article, including the backsheet of FIG. 1;

FIG. 3 shows a schematic cross-section of an absorbent article as inFIG. 2 in the center of the article;

FIG. 4 shows a schematic cross-section of the absorbent article as inFIG. 2 towards the front edge of the article;

FIG. 5 shows an alternative core-to-backsheet glue pattern;

FIG. 6 shows another alternative core-to-backsheet glue pattern;

FIG. 7 shows another alternative core-to-backsheet glue pattern;

FIG. 8 shows another alternative core-to-backsheet glue pattern;

FIG. 9 is a top side view of an exemplary absorbent core in isolation;

FIG. 10 is a transversal cross-section of the core of FIG. 10;

FIG. 11 is a schematic sketch of a process for applying the core tobacksheet glue pattern.

FIG. 11 a,b,c schematically illustrate three different applicators thatmay be used to apply a glue;

FIG. 12 a,b,c illustrate three different discontinuous glue applicationpattern.

DETAILED DESCRIPTION OF THE INVENTION Introduction

As used herein, the terms “comprise(s)” and “comprising” are open-ended;each specifies the presence of the feature that follows, e.g. acomponent, but does not preclude the presence of other features, e.g.elements, steps, components known in the art or disclosed herein. Theseterms based on the verb “comprise” should be read as encompassing thenarrower terms “consisting essentially of” which excludes any element,step or ingredient not mentioned which materially affect the way thefeature performs its function, and the term “consisting of” whichexcludes any element, step, or ingredient not specified. Any preferredor exemplary embodiments described below are not limiting the scope ofthe claims, unless specifically indicated to do so. The words“typically”, “normally”, “preferably”, “advantageously”, “in particular”and the likes also qualify features which are not intended to limit thescope of the claims unless specifically indicated to do so.

Unless indicated otherwise, the description and claims refer to theabsorbent core and article before use (i.e. dry, and not loaded with afluid) and conditioned at least 24 hours at 21° C.+/−2° C. and 50+/−20%Relative Humidity (RH).

The invention will now be further illustrated with reference to theembodiments as described in the Figures. For ease of discussion, theabsorbent article and its components will be discussed with reference tothe numerals referred to in these Figures. However it should beunderstood that these exemplary embodiments and the numerals are notintended to limit the scope of the claims, unless specificallyindicated. Dimensions and values disclosed herein are not to beunderstood as being strictly limited to the exact numerical valuesrecited. Instead, unless otherwise specified, each such dimension isintended to mean both the recited value and a functionally equivalentrange surrounding that value. For example, a dimension disclosed as “40mm” is intended to mean “about 40 mm”.

General Description of FIG. 1

FIG. 1 shows an exemplary core-to-backsheet gluing pattern according tothe invention. For readability, the backsheet 26 is represented incontinuous line and the contour of the absorbent core 28 and of thechannels 26 a, 26 b in broken lines, with other layers of the articlessuch as the topsheet not displayed. The article represented is aso-called taped diaper, which comprise back ears 40 with releasabletapes 42 which can affixed to a so-called landing zone (not represented)on the front waist of the garment-facing side of the article. Thearticle represented also comprises front ears 46 which provide a bettercoverage of the diaper along the front waist of the user. Of course, thecore-to-backsheet gluing pattern of the invention may also be used inso-called pant diapers which have pre-sealed side edges. Some additionallayers and components of the article are shown in FIG. 2, as will bediscussed further below.

The absorbent article 20 comprises a front edge 10, a back edge 12, andtwo longitudinally extending side (lateral) edges 13, 14. The front edge10 is the edge of the article which is intended to be placed towards thefront of the user when worn, and the back edge 12 is the opposite edge.The absorbent article is notionally (i.e. virtually) divided by alongitudinal axis 80 extending from the front edge to the back edge ofthe article and dividing the article in two substantially symmetricalhalves relative to this axis, when viewing the core in the plane formedby the longitudinal direction (y) and the transversal direction (x). Thelongitudinal direction extends along the length of the article, and thetransversal direction is perpendicular to the longitudinal direction.

For ease of discussion, the exemplarily absorbent article is representedin a flat state extending in a transversal direction and a longitudinaldirection. If some part of the article is under tension due toelasticized components, the article may be typically flattened usingclamps along the periphery of the article and/or a sticky surface, sothat the topsheet and backsheet can be pulled taut so as to besubstantially flat. Closed articles such as training pant may be cutopen along the side seams to apply them on a flat surface. Unlessotherwise indicated, dimensions and areas disclosed herein apply to thearticle in this flat-out configuration. The article has a length L″ asmeasured along the axis 80 from the back edge to the front edge.

The backsheet 26 may be generally rectangular as shown in FIG. 1. Shapedbacksheet having a narrower waist thus forming an hour-glass shape arealso known. The backsheet may then form front and back ears thuseliminating the need for additional material for these components.However this construction has other disadvantages such as having tocut-out materials resulting in waste and making it more difficult toelasticize the back ears for example.

The absorbent core 28 and its channels 26 a, 26 b are shown in brokenlines on FIG. 1, and in isolation on FIG. 9. The channels 26 a, 26 b aregenerally longitudinally extending and may be mirror image of each otherrelative to the longitudinal axis. The channels may be curved, as shownin FIG. 1, but the channels may be also straight, in particular straightand orientated in the longitudinal direction. The core-to-backsheetgluing pattern will now be described in details in the following.

First Glue Application Area 100

The core-to-backsheet gluing pattern comprises a first glue, which isapplied on a first glue application area 100 (herein abbreviated as“first glue area”). The first glue area 100 is at least partiallypresent between the channels 26 a, 26 b, as considered from the top ofthe flattened article as shown in FIG. 1. Although there may be someoverlap between the channels and the first glue area, it may beadvantageous that the first glue area does not overlap with thechannels. During use, the absorbent material around the channels mayswell as they absorb a fluid and the channels will become moretridimensional. If the first glue area overlaps the channels, there is arisk that the backsheet will follow the formation of these morepronounced three-dimensional channels. This may create stress in thebacksheet and lead to rupture in the backsheet. Thus it may beadvantageous that the width of the first glue area is smaller than orequal to the smallest distance separating the channels areas 26 a,b. Thefirst glue area 100 may be generally aligned with and may overlap thelongitudinal axis 80 of the article, for example as a slot-coated gluestripe 100 as represented in the Figures.

The dimensions of the first glue area may generally vary and depend ofthe type of article considered, as well as the dimensions of thechannels. The channels may generally extend more in the longitudinaldirection than in the transversal direction. Thus the first glue areamay also extend more in the longitudinal direction. For example, thefirst glue area may have a length which is at least 3 times, or at least5 times longer than it width (as projected on the y and x axisrespectively). The length of the first glue area 100 may for examplerange from 10% to 500% of the length L′ of the channels 26 a,b, forexample from 5 cm to 30 cm for a diaper. The width of the first gluearea may also vary, for example ranging from 0.5 mm to 10 mm for adiaper.

Although not illustrated in the Figures, it is also not excluded thatthe first glue area may comprise a plurality of macroscopic sub-areasseparated from each other. This may be the case for example if the firstglue is intermittently applied to provide a series of longitudinallyaligned succeeding stripes, similar to intermittent road markings. It isalso possible to print the first glue with sub-areas having diverseshapes including recreational shapes such as small characters or toys,in particular if the first glue comprises a pigment so that the firstglue areas is visible through the backsheet on the garment-facing sideof the article. More generally, one of the glues, in particular thefirst glue, may comprise a pigment or other colored substance so that itis visible through the backsheet. The first glue may also not comprise apigment or another colored substance, so that the first glue is notparticularly visible through the backsheet. The first glue may be alsoapplied in a plurality (two or more) of parallel longitudinallyextending stripes. In these other examples, the dimensions of the firstarea as indicated above apply to the sub-areas and the spaces betweenthese sub-areas, taken as a whole.

The first glue has a first glue application pattern within the firstglue application area 100. The application pattern is dependent of themethod used to apply the first glue on the substrate. The first glue maybe in particular applied continuously, meaning that the glue forms a twodimensional continuous layer within the glue application area. Typicallythe first glue may be applied by a contact method, where the applicatordirectly applies the glue on top of the substrate. Advantages of directglue application and example are listed in a publication by the Nordsoncompany at this web address:http://www.nordson.com/en-us/divisions/adhesive-dispensing/Literature/WhitePaper/HoldingItTogetherBylinefromNonwovensReport.pdf. Because there isno distance or only a small distance between the nozzle and thesubstrate, contact deposition allows better control of the adhesiveapplication. A typical contact applicator is a slot-coater. In slotcoating, the adhesive exits the applicator through a thin, widepassageway—see FIG. 10a . Another well-known contact applicationtechnology is glue printing. These contact methods will be detailed inthe process section below.

Using a contact method may typically provide the advantage of providingan accurate first glue application area 100. This may be advantageousbecause the distance between the channels may be relatively small,especially when the channels are curved at their closest positionsrelative to another. Since it may be advantageous to have no or alimited amount of glue in the areas of the channels, a contact methodhas the advantage of a more precise application than a non-contactmethod, such as adhesive spraying. A contact method also allows applyingthe glue continuously in the area of application. This may provide for ahigher basis weight glue attachment per unit of surface, which may be anadvantage as the first glue area may typically be smaller than thesecond glue area. The first glue area is generally limited on its sideedges by the channels.

Second Glue Application Area 110

The core-to-backsheet pattern comprises a second glue on a second glueapplication area 110 (herein abbreviated as second glue area). Thissecond glue area is at least partially outside the area between thechannels 26 a,b, in particular, the second glue may be completely absentfrom the area between the channels. The second glue has a differentapplication pattern than the first glue. This allows providing thesecond glue area with different properties than the first glue area. Asindicated previously, the first glue area 100 may require a precisedeposition on a relatively narrow area at a higher basis weight of glue.The second glue application area 110 should on the other hand be able tocost-effectively cover a relatively large area, several times largerthan the first glue application area, in particular the second glue areamay be at least 3 times larger, or at least 5 times larger, than thefirst glue area. By providing for a larger area of attachment than thefirst glue, the second glue may ensure the overall stability of the corewithin the chassis of the article. The first and second glues may havethe same or different compositions.

The second glue may be advantageously applied at a lower basis weightthan the first glue. For example, the second glue may be applied at abasis weight which is at least 3 times, or at least 5 times lower thanthe basis weight of the first glue (calculated based on the respectivesurface of the application area for each glue). For a baby diaper, thesecond glue may be applied for example at a basis weight of between 0.5to 9 gsm (grams per square meter), in particular 1-5 gsm, and the firstglue at a basis weight of between 5 to 100 gsm, in particular 10-50 gsm.However the article may comprise less of the first glue in absoluteamount than the second glue because of the areas difference. The totalamount of first glue in an article (in particular a diaper) may forexample range from 5 to 100 mg per article, in particular 10-50 mg,whereas the total amount of the first second glue may for example rangefrom 25 to 300 mg, in particular 50-150.

Various designs for the second glue area 110 are possible. The secondglue area may be unitary, as illustrated on FIGS. 1, 5-7 but it is notexcluded that it comprises discrete macroscopic sub-areas or portionsseparated from another, as for example shown on FIG. 8 with twolongitudinally extending discrete portions 1113, 1114.

The second glue area may advantageously extend, at least portion-wise,across the full length of the core and furthermore along the full lengthof the backsheet. These longitudinally-extending portions are indicatedby reference 1113, 1114 in the Figures. This provides for full lengthattachment of the core to the backsheet. When the second glue areaextends longitudinally beyond the core, it can further provide forattachment of the topsheet to the backsheet forward and backward of thecore. The second glue application area 110 may also comprise front andback portions 1110, 1112 which are relatively large in the transversaldirection, in particular that overlap or cover the entire front edge 10and back edge 12 of the core and backsheet to provide for a strongerattachment of the core in these areas 1110, 1112. These transversallyextending sub-areas may provide that the absorbent core has no freecorners which may be more easily subject to delamination. In summary,the second glue area as a whole may generally have a roman II numeralshape when seen from above, as shown in FIG. 1, but other shapes arepossible.

As indicated previously, the first channel and the second channel are atleast partially not attached to the backsheet by the first or secondglue, or otherwise. The channels may be advantageously not substantiallyattached by the first and second glue, or otherwise, to the backsheet.By “not substantially attached”, it is meant that less than 25% of thelength of each channel is attached to the backsheet. For example, onlythe ends of the channels may be attached by the second glue as shown onFIG. 1.

Whereas the first and second glues may have the same or differentcompositions, the second glue application pattern is different from thefirst glue application pattern. The second glue application pattern mayin particular be discontinuous. By discontinuous, it is meant that thesecond glue does not form a continuous layer on the application area (oreach sub-areas if several sub-areas are present). The second glueapplication pattern may for example comprise filaments, fibers or thelike creating a more or less regular web with relatively large areasbetween the glue filaments or fibers which are not covered by glue.Examples of these patterns are illustrated in FIG. 12a-c for example(spiral, mini swirls, and random pattern respectively).

As for the first glue, the application pattern of the second glue willbe typically determined by the application device used. A non-contactapplication method such as glue spraying is advantageous. Non-contactmethods allow the coverage of relatively large areas for an economicaluse of glue material. The Nordson company reference document referred toabove gives a good overview of usual non-contact glue applicators knownin the art for gluing components of a diaper with an adhesive. Thesecond glue application pattern may in particular comprise a pluralityof spray nozzles that spray large swirls (also called “spiral” gluepattern, and illustrated on FIG. 12a ), mini swirls (illustrated in FIG.12b ) or random fibrous glue patterns (illustrated in FIG. 12c ). Thedifferent application devices will now be further illustrated below withreference to FIG. 11, which illustrates a process for applying the firstand second glue between the backsheet and the core. The second gluepattern could also be applied by a printing glue technology which allowsa better control on the pattern application but allows a well definedpattern for example less than 50% of coverage area.

Alternative Designs (FIGS. 5-8)

FIG. 1 discloses a core-to-backsheet gluing pattern wherein the firstglue area is a stripe between the channels and the second glue areagenerally resembles roman II numeral outline.

Alternative gluing pattern are of course possible, some of which aredisclosed in FIGS. 5 to 8. FIG. 5 for example show an alternativepattern wherein the glue stripe of the first glue area is longer than inFIG. 1 and overlap towards its extremities with the second glue area.FIG. 6 shows another alternative design wherein the front and backportions 1110, 1112 of the second glue area are not unitary but comprisea separate central sub-area. This design allows reducing the amount ofsecond glue used while still providing the benefits of gluing all fourcorners of the absorbent core to the backsheet.

The longitudinally extending portions 1113, 1114 of the absorbent coremay be typically present inwardly of the longitudinal side edges 284,286 of the core as shown in FIG. 1, but it is not excluded that theseportions 1113, 1114 overlap with the side edges 284,286 of the core, asillustrated in FIG. 7.

In a simplified design as illustrated on FIG. 8, the second glue areamay be comprised of only two separate portions 1113, 1114 extendingalong the full length of the core and the backsheet. These portions maybe placed inwardly of the side edges of the core (as shown in FIG. 8) ormay be placed further outwardly transversally to also cover the sideedges of the cores along their whole length, including the four cornersof the core (not represented).

Process for Applying the First Glue and the Second Glue

The first glue and the second glue may be applied as schematicallyrepresented on FIG. 11, although other processes and variations thereofmay of course be used. The process for making and assembling the rest ofthe absorbent article may be according any known processes in the artand will not be further detailed herein. The exemplary process of FIG.11 shows the backsheet coming as a first continuous web feed 26 from theleft side of the Figure and passing successively through two glueapplicators. The first glue applicator 102 applies the first glue on thefirst glue application area 100. As indicated previously, this firstglue applicator is advantageously a contact glue applicator, inparticular for simplicity and cost a slot-coater 102 comprising a slotcoating nozzle 104 (FIG. 11a ) through which the slot glue is applieddirectly onto the backsheet. In slot coating, the adhesive exits theapplicator through a thin, wide passageway—the nozzle laying theadhesive directly down on top of the substrate. The glue stripe can varyin width and pattern, depending on the application needs.

Other contact methods exist, for example as disclosed in US2011/0274834(Brown). This document discloses a method and apparatus for theapplication of viscous fluids, such as adhesives, in pre-determinedpatterns to an advancing substrate. The fluid application apparatus mayinclude a slot die applicator and a substrate carrier. The substratecarrier may include one or more pattern elements and may be adapted toadvance the substrate past the slot die applicator as the slot dieapplicator discharges adhesive onto the substrate. In operation, thesubstrate is disposed on the substrate carrier; the substrate carrieradvances the substrate past the slot opening of the slot die applicator.In turn, the substrate is intermittently compressed between the slot dieapplicator and the pattern surface of the pattern element. As thesubstrate is intermittently compressed, adhesive discharged from theslot die applicator is applied onto the substrate in an area having ashape substantially the same as a shape defined by the pattern surface.US2008/221543 (Wilkes) discloses another contact method for applying acolored hot-melt adhesive which may be used as a graphic. U.S. Pat. No.6,033,513 (Nakamura) discloses an improved roll transfer coating methodfor hot melt adhesive as well as some roll transfer process of the priorart, all of which may also be used herein.

Directly after this first glue application, a second glue applicator 112applies the second glue on the desired second glue application area 110according to the second glue application pattern. The second glueapplicator may be in particular a non-contact applicator. The secondglue applicator 112 may comprise a plurality of nozzles 114 b, 114 cinstalled in parallel as represented on FIGS. 11b and 11c . In theexample described, the second applicator 112 comprises 6 nozzles whichcan be independently controlled and turned on and off to form thedesired second glue area such as the roman numeral II of FIGS. 1, 5 and7. In another example, the second applicator device may comprise 5 suchnozzles, with the third nozzles separated by a gap from the twoneighboring nozzles, to provide for a second glue application are asshown on FIG. 6. In another example, the second applicator 102 may forexample comprise only two nozzles on each side of the longitudinal axisto provide a second glue application area as shown on FIG. 8.

The individual spray nozzles of the second glue applicator may be of anytype known in the art. In a first applicator example 112 b, the nozzlesmay be for example as available from Nordson under the designation “CFapplicator”. These nozzles each deliver a single large swirl (alsocalled spiral) from each nozzle 114 b, as illustrated on FIG. 12a . Thewidth of such large spiral may for example range from 10 mm to 30 mm. Inthe case of 6 such nozzles 114 b installed in parallel, byintermittently turning on and off some of the nozzles (for examplenozzles 1, 3, 4 and 6) and leaving two nozzles (2 and 5) continuouslyon, a roman II pattern can be repeatedly applied on an substrate such asthe backsheet web feed. The same principle of placing in parallel aplurality of nozzles to apply the desired pattern works for otherapplicators. The second glue may be in particular applied by anapplicator 114 c comprising several nozzle units 114 c with a pluralityof so-called mini-swirl nozzles, for example available from Nordsonunder the “Summit” designation. Each of these nozzle units 114 c has aplurality, in particular three as represented for nozzle 114 c, ofsub-nozzles that together distribute several small swirls of adhesive(as illustrated on FIG. 12b ). Each unit may apply a plurality of swirlshaving together the same width as indicated previously for one largeswirl/spiral pattern. These nozzle units may also be independentlyturned on and off to provide the desired area of coverage. Mini-swirlscan be used at a faster speed than large swirl/spiral and have a betteredge definition, while not being as precise as slot application. Ofcourse any other known spraying nozzle type may be used, for examplenozzle spraying a random pattern of glue, such as those supplied byNordson under the “Signature” spray nozzle designation. These nozzlesmay produce random pattern of glue in fibrous form. Although randomlysprayed, the adhesive filaments may appear as being generallylongitudinally aligned (see illustration of FIG. 12c ) due to themovement of the web at high speed. An air flow may be used inconjunction with a spray nozzle to direct or disperse the gluefilaments.

In addition, the second glue application area may advantageously extendforwards and backwards of the absorbent core to provide for extendedareas of gluing of the backsheet with the topsheet for example. Thefront and back glue portions 1110, 1112 which may be relatively large tocover the front and back edges of the core may be separated by anintermediate area with a lesser amount of second glue coverage. Theintermittently functioning nozzles (numbers 1, 3, 4 and 6 in thisexample) may be turned off for the intermediate area between the areas1110, 1112. This allows material savings, as well as giving more freedomof movement of the core relative to the backsheet in this intermediatearea. The intermittently functioning nozzles may be switched on and offonly once for each individual core-to-backsheet gluing pattern. Forexample, the intermittent nozzles are switched on to form the largerback second glue portion 1112, and remain on to form the front largersecond glue portion 1110 of the following gluing pattern, before beingswitched off for the intermediate middle region of this following gluingpattern.

It may be advantageous, as represented, to apply the first glue beforethe second glue, in particular when the first glue is applied with acontact applicator and second glue is applied with a non-contactapplicator. Otherwise, there could be a risk of smearing the second glueon the contact applicator of the first glue. Similarly, it may beadvantageous to apply the first and second glue onto the backsheetrather than the absorbent core, as the backsheet is a continuous web ofmaterial that will be typically easier to handle and can provide for acontinuous application of the second glue over two succeedingcore-to-backsheet gluing pattern.

After the glues have been applied, the feed of absorbent cores, as showncoming from the right, is then synchronized with the glue applicationpatterns of the backsheet so that when the backsheet and absorbent coreare brought in face-to-face contact with some pressure, they areattached by the first glue and second glue. The feed of absorbent coresmay be supported on a continuous substrate which may be a component ofthe article. The supporting substrate for the absorbent cores may be inparticular the remaining components of the article which have beenpre-assembled on the line, with the topsheet 24 being the largest ofthese components on which the other have been assembled. The articlesare then individualized for example by die cutting. Of course, otherglues or attachment means, such as a chassis side slots on each of thelongitudinal edges 13, 14 may be added to form the longitudinal sealsbetween the backsheet and the topsheet and/or barrier leg cuffs of thefinal articles. These additional glues or other attachment means are notrepresented in the Figures for simplicity but may be as is known fromany conventional absorbent articles.

Composition of the First Glue and the Second Glue

The first glue and second glue may be any type of glue known in the artand suitable to be applied according to the desired application pattern.The first glue and the second glue composition may be the same ordifferent. In particular, any kind of thermoplastic hot-melt adhesivesused in the field of absorbent article making may be suitable. Such anadhesive generally includes one or more polymers to provide cohesivestrength (e.g., aliphatic polyolefins such as ethylene-propylenecopolymers, polyetheramides, polyetheresters, and combinations thereof;ethylene vinyl acetate copolymers; styrene-butadiene or styrene-isopreneblock copolymers; etc.), a resin or analogous material (sometimes calleda tackifier) to provide adhesive strength (e.g., hydrocarbons distilledfrom petroleum distillates; rosins and/or rosin esters; terpenesderived, for example, from wood or citrus, etc.); and optional waxes,plasticizers or other materials to modify viscosity (e.g., mineral oil,polybutene, paraffin oils, ester oils, and the like), and/or otheradditives including, but not limited to, antioxidants or otherstabilizers. Further information about hotmelt adhesive chemistry isdiscussed below for the fibrous thermoplastic adhesive layer that may beused in the absorbent core.

Exemplary suitable commercial adhesives for the first and/or second glueare available from Fuller under reference number 1286 or 1358, or fromNational Starch & Chemical under reference number DM 526, DM538 orDM3800.

General Description of the Absorbent Core 28

As used herein, the term “absorbent core” refers to a component of theabsorbent article which comprises an absorbent material enclosed in acore wrap. As used herein, the term “absorbent core” does not includethe topsheet, the backsheet and (if present) an acquisition-distributionlayer or multilayer system, which is not integral part of the absorbentcore, in particular which is not placed within the core wrap. Theabsorbent core is typically the component of an absorbent article thathas the most absorbent capacity of all the components of the absorbentarticle and which comprises all, or at least the majority of,superabsorbent polymer (SAP). The core may consist essentially of, orconsist of, the core wrap, the absorbent material and adhesives. Theterms “absorbent core” and “core” are herein used interchangeably.

An exemplary core 28 that can be used in the invention is represented inFIGS. 9-10. The absorbent cores can typically be laid flat on a surfaceas shown on FIG. 9. The absorbent cores may also be typically thin andconformable, so that they can also be laid on a non-flat surface forexample a drum during their making process or stored as a continuousroll of stock material before being converted into an absorbent article.For ease of discussion, the exemplarily absorbent core of FIG. 9 isrepresented in a flat state and extending in a transversal direction anda longitudinal direction. Unless otherwise indicated, dimensions andareas disclosed herein apply to the core in this flat-out configuration.The same applies to the absorbent article in which the core isintegrated.

The absorbent core can typically be generally rectangular with a width Win the transversal direction and a length L in the longitudinaldirection as measured from edge to edge, including the region of thecore wrap which does not enclose the absorbent material, in particularat the front and back ends 280, 282, which may be sealed. In case thecore is not rectangular, the maximum dimension measured along thetransversal and longitudinal direction can be used to report the lengthand width of the core. The width and length of the core may varydepending on the intended usage. For baby and infant diapers, the widthL may for example in the range from 40 mm to 200 mm and the length from100 mm to 500 mm, as measured along the longitudinal axis 80′ of thecore. The longitudinal axis 80′ of the core may be contiguous with thelongitudinal axis 80 of the article. The article further comprises aliquid permeable topsheet 24 and a liquid impermeable backsheet 25 withthe absorbent core 28 positioned between the topsheet and the backsheet.

The absorbent core comprises a front edge 280, a back edge 282 and twolongitudinally extending side edges 284, 286 joining the front edge andthe back edge. The front edge of the core is the edge of the coreintended to be placed towards the front edge of the absorbent article.Typically the absorbent material 60 of the core may be advantageouslydistributed in somewhat higher amount towards the front edge thantowards the back edge as more absorbency is typically required towardsthe front half of the article. Typically the front and back edges 280,282 of the core may be shorter than the side edges 284, 286 of the core.The absorbent core may also comprise a top side 288 and a bottom side290. The top side of the core is the side placed or intended to beplaced towards the topsheet 24 of the article and the bottom side is theside placed or intended to be placed towards the backsheet 25 in thefinished article. The top side of the core wrap is typically morehydrophilic than the bottom side.

The transversal axis of the core (herein also referred to as “crotchline”), is defined as the virtual line perpendicular to the longitudinalaxis and passing through the crotch point C of the core. The crotchpoint C is defined as the point of the absorbent core placed at adistance of 0.45 of L from the front edge of the absorbent core, L beingthe length of the core as measured from the front edge 280 in directionof the back edge 282, as shown on FIG. 9.

The following will provide an exemplary description of possible corecomponents. Further details are described for example in WO2012/170778(Rosati et al.), WO2014/93311A1 (Arizti et al), WO2014/093310(Ehrnsperger et al.), which disclose absorbent structures that comprisesuperabsorbent polymers, optionally a cellulosic material, and at leasta pair of substantially longitudinally extending channels.

Core Wrap 16, 16′

The core wrap may comprise a first substrate 16 generally forming thetop side of the core and a second substrate 16′ generally forming thebottom side of the core wrap. The first and second substrates may beformed by two different materials, as shown in FIG. 10, but any otherknown core wrap constructions may also be used, for example wherein thecore wrap is formed of a single material with one single longitudinalseal. The first and second substrates can be attached by gluing orotherwise to form at least one C-wrap seal 72 along each of the sideedges 284, 286 of the core. The first and second substrates may be anonwoven web, such as a laminate comprising spunbond (“S”) or meltblown(“M”) layer. For example spunmelt polypropylene nonwovens are suitable,in particular those having a laminate web SMS, or SMMS, or SSMMS,structure, and having a basis weight range of about 5 gsm to 15 gsm.Suitable materials are for example disclosed in U.S. Pat. No. 7,744,576,US 2011/0268932 A1, US 2011/0319848 A1 and US 2011/0250413 A1. Thebottom substrate 16′ may be inherently hydrophobic but air-permeable,and the top substrate 16 may be hydrophillically treated. There may be aseal along the front edge 282 and back edge 280 of the core wrap.

Combining the auxiliary glue layer with a C-wrap seal along at least oneand preferably two longitudinal edges of the core, and optionally afurther fibrous adhesive web (not represented), can provide animmobilization of the absorbent material in dry and wet state. Theabsorbent core may in general advantageously achieve an SAP loss of nomore than about 70%, 60%, 50%, 40%, 30%, 20%, or 10% according to theWet Immobilization Test described in US2010/0051166A1.

Absorbent Material 60

The absorbent material in the core can comprise a relatively highproportion of superabsorbent polymer (herein abbreviated as “SAP”)enclosed within the core wrap. The SAP content may represent inparticular at least 85%, 90%, 95% and up to 100%, of superabsorbentpolymer by weight of the absorbent material. The absorbent material mayin particular comprise no or only small amount of cellulose fibers, suchas less than 20%, in particular less than 10%, 5% or even 0% ofcellulose fibers by weight of the absorbent material. The absorbentmaterial may thus advantageously consist or consist essentially of SAP.The SAP may be typically in particulate forms (superabsorbent polymerparticles), but it not excluded that other form of SAP may be used suchas a superabsorbent polymer foam for example. The absorbent core maythus be relatively thin, in particular thinner than conventional corescomprising cellulosic fibers. In particular, the caliper of the core(before use) as measured at the crotch point (C) or at any other pointsof the surface of the core according to the Core Caliper Test asdescribed herein may be from 0.25 mm to 5.0 mm, in particular from 0.5mm to 4.0 mm.

The term “superabsorbent polymer” refers herein to absorbent materials,which may be cross-linked polymer, and that can typically absorb atleast 10 times their weight of an aqueous 0.9% saline solution asmeasured using the Centrifuge Retention Capacity (CRC) test (EDANAmethod WSP 241.2-05E). The SAP may in particular have a CRC value ofmore than 20 g/g, or more than 24 g/g, or of from 20 to 50 g/g, or from20 to 40 g/g, or 24 to 30 g/g. The fluid permeability of asuperabsorbent polymer can be quantified using its Urine PermeabilityMeasurement (UPM) value, as measured in the test disclosed Europeanpatent application EP2,679,209. The UPM of the SAP may for example be ofat least 10×10⁻⁷ cm³·sec/g, or at least 30×10⁻⁷ cm³·sec/g, or at least50×10⁻⁷ cm³·sec/g, or more, e.g. at least 80 or 100×10⁻⁷ cm³·sec/g.

Absorbent Material Deposition Area 8

The absorbent material 60 defines an absorbent material deposition area8, as seen from above within the plane of the core. The absorbentmaterial deposition area 8 is defined by the periphery of the layer ofabsorbent material 60 within the core wrap, as seen from the top side ofthe absorbent core as shown on FIG. 9, and comprises the channel areas26 a,b encompassed within. The absorbent material deposition area 8 canbe generally rectangular, for example as shown in FIG. 9, but othershapes can also be used such as a “T” or “Y” or “sand-hour” or“dog-bone” shape. In particular the deposition area may show a taperingalong its width at the crotch region of the core. In this way, theabsorbent material deposition area may have a relatively narrow width inan area of the core intended to be placed in the crotch region of theabsorbent article. This may provide for example better wearing comfort.

Channels 26 a,b

The absorbent cores comprise at least two channels 26 a,b (also referredto herein as “channel areas”). The term “channel” designates alongitudinally extending area of the core comprising less absorbentmaterial than the surrounding areas so that an insulting fluid can bequickly distributed along the channel towards the front and back of thecore. The channels may be in particular substantially free of absorbentmaterial. By “substantially free” it is meant that in each of theseareas the basis weight of the absorbent material is at least less than25%, in particular less than 20%, less than 10%, of the average basisweight of the absorbent material in the rest of the absorbent materialdeposition area of the core. In particular there can be no absorbentmaterial in these areas 26 ab. Minimal amount such as involuntarycontaminations with absorbent material particles that may occur duringthe making process are not considered as absorbent material. Thechannels 26 are advantageously surrounded by the absorbent material,when considering the plane of the core, which means that the areas 26 donot extend to any of the edges of the deposition area 8 of the absorbentmaterial 60.

The top layer 16 and the bottom layer 16′ of the core wrap may be bondedto each other through these channel 26 a,b. The bond 27 between thesubstrates in these area may be at least partially formed by anauxiliary glue 71 applied directly to the inner surface of at least oneof the substrate, but other bonding methods are not excluded. Thisbonding allows the channels 26 to form more pronounced three-dimensionalchannels 26′ as the absorbent material swells when it absorbs a liquidsuch as urine. Examples of channels according to the invention aredescribed in details for example in WO2012/170778 (Rosati et al.),WO2014/93311A1 (Arizti et al), WO2014/093310 (Ehrnsperger et al.) whichdisclose absorbent structures that comprise superabsorbent polymers,optionally a cellulosic material, and at least a pair of substantiallylongitudinally extending channels.

When the absorbent material 60 swells upon absorbing a liquid, the corewrap bonds 27 remain at least initially attached in the channel areas26. The absorbent material 60 swells in the rest of the core when itabsorbs a liquid, so that the core wrap forms one or more pronouncedchannels along the core wrap bond 27. These channels are threedimensional and can serve to distribute an insulting fluid along theirlength to a wider area of the core. They may provide a quicker fluidacquisition speed and a better utilization of the absorbent capacity ofthe core.

The absorbent core 28 comprise at least a first and second channels 26ab disposed on each side of the longitudinal axis 80′. It is notexcluded that the core may also comprise more than two channels. Shorterchannel areas substantially free of absorbent material may also bepresent, for example in the back region or the front region of the core,as seen for example in the Figures of WO2012/170778.

The channels may extend substantially longitudinally, which meanstypically that each area extends at least as much in the longitudinaldirection (y) than in the transversal direction (x), and typically atleast twice as much in the longitudinal direction than in the transversedirection (as measured after projection on the respective axis). Thechannels 26 may have a length L′ projected on the longitudinal axis 80of the core that is at least 10% of the length L of the absorbent core,in particular from 20% to 80%. The channels may have an areasubstantially free of absorbent material having a width We along atleast part of their length which is at least 2 mm, or at least 3 mm orat least 4 mm, up to for example 20 mm, or 16 mm or 12 mm. The width Wemay be constant through substantially the whole length or may vary alongthe length of the channels.

The channels 26 may be curved as shown in the Figures but they may bealso straight and parallel to the longitudinal axis. It may beadvantageous that there is no channels that coincide with thelongitudinal axis 80′ of the core. When present as a pair of channels 26a,b, these may be spaced apart from one another over their wholelongitudinal dimension. The smallest spacing distance may be for exampleat least 5 mm, or at least 10 mm, or at least 16 mm.

Process for Making the Core

The absorbent material 60 may be deposited on any of the substrates 16,16′ using known techniques. In particular the SAP printing technology asdisclosed for example in US2006/024433 (Blessing), US2008/0312617 andUS2010/0051166A1 (both to Hundorf et al.), which allow relativelyprecise deposition of SAP at relatively high speed may be used. Thistechnique uses a transfer device such as a printing roll to deposit SAPonto a substrate disposed on a grid of a support which may include aplurality of cross bars extending substantially parallel to and spacedfrom one another. Channel areas 26 substantially free of absorbentmaterial can be formed for example by modifying the pattern of the gridand receiving drums so that no SAP is applied in the selected areas, asexemplary disclosed in US2012/0312491 (Jackels). This technology allowshigh-speed and precise deposition of SAP on a substrate in particular toprovide one or more area(s) 26 substantially free of absorbent materialsurrounded by absorbent material. US2014/027066 (Jackels) furtherdiscloses specific raised strips and mating strips on the equipment forbonding the core substrates through the channel areas.

The absorbent material may be substantially continuously distributed inthe deposition area 8. By “substantially continuous” it is meant that atleast 50%, or at least to 70% and up to 100% of the deposition areacomprises a continuous layer of absorbent material as seen from the topside of the core. The absorbent material may be for example applied as asingle continuous layer on one of the substrate, the layer thus directlyforming the material deposition area 8. A continuous layer of absorbentmaterial, in particular of SAP, may also be obtained by combining twoabsorbent layers having matching discontinuous absorbent materialapplication pattern wherein the resulting layer is substantiallycontinuously distributed across the absorbent material deposition area,as exemplarily taught in US2008/0312622A1 (Hundorf).

Microfiber Glue

The absorbent core 28 may also comprise a fibrous thermoplastic adhesivematerial, to further immobilize the absorbent material 60 during themaking process of the core and usage of the article. The fibrousthermoplastic adhesive material may be in particular useful toimmobilize a dual layers of absorbent material to their respectivesubstrate 16, 16′. Each of these absorbent layers may comprise landareas separated by junction areas and the fibrous thermoplastic adhesivematerial may then be at least partially in contact with the absorbentmaterial in the land areas and at least partially in contact with thesubstrate layer 16, 16′ in the junction areas. This imparts anessentially three-dimensional net-like structure to the fibrous layer ofthermoplastic adhesive material, which in itself is essentially atwo-dimensional structure of relatively small thickness, as compared tothe dimension in length and width directions. Thereby, the fibrousthermoplastic adhesive material may provide cavities to cover theabsorbent material in the land areas, and thereby immobilizes thisabsorbent material. The fibrous adhesive may be for example sprayed onan absorbent layer after it has been deposited on its substrate duringthe core making process.

The fibrous thermoplastic adhesive material may typically have amolecular weight (Mw) of more than 10,000 and a glass transitiontemperature (Tg) usually below room temperature or −6° C.<Tg<16° C.Typical concentrations of the polymer in a hotmelt are in the range ofabout 20% to about 40% by weight. The thermoplastic polymers may bewater insensitive. Exemplary polymers are (styrenic) block copolymersincluding A-B-A triblock structures, A-B diblock structures and (A-B)nradial block copolymer structures wherein the A blocks arenon-elastomeric polymer blocks, typically comprising polystyrene, andthe B blocks are unsaturated conjugated diene or (partly) hydrogenatedversions of such. The B block is typically isoprene, butadiene,ethylene/butylene (hydrogenated butadiene), ethylene/propylene(hydrogenated isoprene), and mixtures thereof. Other suitablethermoplastic polymers that may be employed are metallocene polyolefins,which are ethylene polymers prepared using single-site or metallocenecatalysts. Therein, at least one comonomer can be polymerized withethylene to make a copolymer, terpolymer or higher order polymer. Alsoapplicable are amorphous polyolefins or amorphous polyalphaolefins(APAO) which are homopolymers, copolymers or terpolymers of C2 to C8alpha olefins.

The tackifying resin may exemplarily have a Mw below 5,000 and a Tgusually above room temperature, typical concentrations of the resin in ahotmelt are in the range of about 30 to about 60%, and the plasticizerhas a low Mw of typically less than 1,000 and a Tg below roomtemperature, with a typical concentration of about 0 to about 15%.

The thermoplastic adhesive used for the fibrous layer preferably haselastomeric properties, such that the web formed by the fibers on theSAP layer is able to be stretched as the SAP swell. Exemplaryelastomeric, hotmelt adhesives include thermoplastic elastomers such asethylene vinyl acetates, polyurethanes, polyolefin blends of a hardcomponent (generally a crystalline polyolefin such as polypropylene orpolyethylene) and a Soft component (such as ethylene-propylene rubber);copolyesters such as poly(ethylene terephthalate-co-ethylene azelate);and thermoplastic elastomeric block copolymers having thermoplastic endblocks and rubbery mid blocks designated as A-B-A block copolymers:mixtures of structurally different homopolymers or copolymers, e.g., amixture of polyethylene or polystyrene with an A-B-A block copolymer;mixtures of a thermoplastic elastomer and a low molecular weight resinmodifier, e.g., a mixture of a styrene-isoprenestyrene block copolymerwith polystyrene; and the elastomeric, hot-melt, pressure-sensitiveadhesives described herein. Elastomeric, hot-melt adhesives of thesetypes are described in more detail in U.S. Pat. No. 4,731,066 (Korpman).

The thermoplastic adhesive material fibers may exemplarily have anaverage thickness of about 1 to about 50 micrometers or about 1 to about35 micrometers and an average length of about 5 mm to about 50 mm orabout 5 mm to about 30 mm. The auxiliary glue may improve the adhesionof the thermoplastic adhesive material to the substrate. The fibersadhere to each other to form a fibrous layer, which can also bedescribed as a mesh. This is further detailed in the Rosati and Jackelsreferences previously indicated.

General Description of the Absorbent Article 20

The absorbent article 20 comprises a liquid permeable topsheet 24, aliquid impermeable backsheet 25 and an absorbent core 28 according tothe invention between the topsheet 24 and the backsheet 25. Some typicalcomponents of a baby taped diaper 20 are further represented in FIG. 2in exploded view, and in cross-section view in FIGS. 3-4. Typically allcomponents will be attached to the other neighboring components by glue,heat and pressure bonding, or otherwise, but only the core-to-backsheetgluing pattern is represented in these Figures for readability. Theabsorbent article may also comprise further typical components such asan acquisition layer 52 and/or a distribution layer 54, elasticizedgasketing cuffs 32 within the chassis and partially upstanding barrierleg cuffs 34. The Figures also show other typical taped diapercomponents such as a fastening system comprising fastening tabs 42attached towards the back edge 12 of the article and cooperating with alanding zone towards the front edge 10 of the article. The absorbentarticle may also comprise other typical components, which are notrepresented in the Figures, such as a back elastic waist feature, afront elastic waist feature, transverse barrier cuffs, a lotionapplication, a wetness indicator that reacts with urine such as a pHindicator which may be incorporated in the first or second glues, inparticular the first glue, etc.

The topsheet 24, the backsheet 25, the absorbent core 28 and the otherarticle components may be assembled in a variety of well-knownconfigurations, in particular by gluing and/or heat embossing. Exemplarydiaper assemblies are for example generally described in U.S. Pat. No.3,860,003, U.S. Pat. No. 5,221,274, U.S. Pat. No. 5,554,145, U.S. Pat.No. 5,569,234, U.S. Pat. No. 5,580,411, and U.S. Pat. No. 6,004,306. Theabsorbent article is preferably thin. The article may be advantageouslythin at the intersection of the longitudinal and transversal axes, forexample with a caliper of from 1.0 mm to 8.0 mm, in particular from 1.5mm to 6.0 mm, as measured using the Absorbent Article Caliper Testdescribed below.

These and other components of the article will now be discussed in moredetail.

Topsheet 24

The topsheet 24 forms at least a part of wearer-facing side of theabsorbent article and is directly in contact with the wearer's skin. Thetopsheet 24 can be joined to the backsheet 25, the absorbent core 28and/or any other layers as is known in the art (as used herein, the term“joined” encompasses configurations whereby an element is directlysecured to another element by affixing the element directly to the otherelement, and configurations whereby an element is indirectly secured toanother element by affixing the element to intermediate member(s) whichin turn are affixed to the other element). Usually, the topsheet 24 andthe backsheet 25 are joined directly to each other in some locations(e.g. on or close to the periphery of the article) and are indirectlyjoined together in other locations by directly joining them to one ormore other elements of the article 20.

The topsheet 24 is preferably compliant, soft-feeling, andnon-irritating to the wearer's skin. Further, at least a portion of thetopsheet 24 is liquid permeable, permitting liquids to readily penetratethrough its thickness. A suitable topsheet may be manufactured from awide range of materials, such as porous foams, reticulated foams,apertured plastic films, or woven or nonwoven materials of naturalfibers (e.g., wood or cotton fibers), synthetic fibers or filaments(e.g., polyester or polypropylene or bicomponent PE/PP fibers ormixtures thereof), or a combination of natural and synthetic fibers.Typical diaper topsheets have a basis weight of from about 10 to about28 gsm, in particular between from about 12 to about 18 gsm but otherbasis weights are possible.

Suitable formed film topsheets are also described in U.S. Pat. No.3,929,135, U.S. Pat. No. 4,324,246, U.S. Pat. No. 4,342,314, U.S. Pat.No. 4,463,045, and U.S. Pat. No. 5,006,394. Other suitable topsheets maybe made in accordance with U.S. Pat. No. 4,609,518 and U.S. Pat. No.4,629,643. Such formed films are available from The Procter & GambleCompany of Cincinnati, Ohio as “DRI-WEAVE” and from TredegarCorporation, based in Richmond, Va., as “CLIFF-T”.

Any portion of the topsheet may be coated with a lotion as is known inthe art. Examples of suitable lotions include those described in U.S.Pat. No. 5,607,760, U.S. Pat. No. 5,609,587, U.S. Pat. No. 5,643,588,U.S. Pat. No. 5,968,025 and U.S. Pat. No. 6,716,441. The topsheet 24 mayalso include or be treated with antibacterial agents, some examples ofwhich are disclosed in WO 95/24173. Further, the topsheet, the backsheetor any portion of the topsheet or backsheet may be embossed and/or mattefinished to provide a more cloth like appearance.

The topsheet 24 may comprise one or more apertures to ease penetrationof exudates there-through, such as urine and/or feces (solid,semi-solid, or liquid). Examples of apertured topsheet are disclosed inU.S. Pat. No. 6,632,504. WO 2011/163582 also discloses suitable coloredtopsheet having a basis weight of from 12 to 18 gsm and comprising aplurality of bonded points. Each of the bonded points has a surface areaof from 2 mm² to 5 mm² and the cumulated surface area of the pluralityof bonded points is from 10 to 25% of the total surface area of thetopsheet.

Backsheet 25

The backsheet 25 is generally that portion of the absorbent article 20which forms the majority of the external surface of the article whenworn by the user. The backsheet 25 is positioned towards the bottom side290 of the absorbent core 28 and prevents the exudates absorbed andcontained therein from soiling articles such as bed sheets andundergarments. The backsheet 25 is typically impermeable to liquids(e.g. urine). The backsheet 25 may for example be or comprise a thinplastic film, on the exterior surface of which a thin non-woven may beattached to improve the feel to the touch. Exemplary backsheet filmsinclude those manufactured by Tredegar Corporation, based in Richmond,Va., and sold under the trade name CPC2 film. Other suitable backsheetmaterials may include breathable materials which permit vapors to escapefrom the article 20 while still preventing exudates from passing throughthe backsheet 25. Exemplary breathable materials may include materialssuch as woven webs, nonwoven webs, composite materials such asfilm-coated nonwoven webs, microporous films such as manufactured byMitsui Toatsu Co., of Japan under the designation ESPOIR NO and byTredegar Corporation of Richmond, Va., and sold under the designationEXAIRE, and monolithic films such as manufactured by Clopay Corporation,Cincinnati, Ohio under the name HYTREL blend P18-3097. Some breathablecomposite materials are described in greater detail in WO 95/16746 (E.I. DuPont), U.S. Pat. No. 5,938,648 (LaVon et al.), U.S. Pat. No.4,681,793 (Linman et al.), U.S. Pat. No. 5,865,823 (Curro), U.S. Pat.No. 5,571,096 (Dobrin et al.) and U.S. Pat. No. 6,946,585 (LondonBrown).

Acquisition and Distribution Layers 52, 54

The absorbent articles of the invention may comprise an acquisitionlayer 52, a distribution layer 54, both, or a single layer having bothfunctions of acquiring and distributing the fluid. Typically, theselayers do not comprise SAP as this may slow the acquisition anddistribution of the fluid. The prior art discloses many type ofacquisition-distribution system, see for example WO 2000/59430 (Daley),WO 95/10996 (Richards), U.S. Pat. No. 5,700,254 (McDowall), WO 02/067809(Graef).

The function of an acquisition layer is to quickly acquire the fluidaway from the topsheet so as to provide a good dryness for the wearer.The acquisition layer is typically placed directly under the topsheet.If present, the distribution layer may be at least partially disposedunder the acquisition layer. The acquisition layer may typically be orcomprise a non-woven material, for example a SMS or SMMS material,comprising a spunbonded, a melt-blown and a further spunbonded layer oralternatively a carded chemical-bonded nonwoven. The non-woven materialmay in particular be latex bonded. Exemplary upper acquisition layers 52are disclosed in U.S. Pat. No. 7,786,341. Carded, resin-bonded nonwovensmay be used, in particular where the fibers used are solid round orround and hollow PET staple fibers (50/50 or 40/60 mix of 6 denier and 9denier fibers). An exemplary binder is a butadiene/styrene latex.Nonwovens have the advantage that they can be manufactured outside theconverting line and stored and used as a roll of material. Furtheruseful nonwovens are described in U.S. Pat. No. 6,645,569 (Cramer etal.), U.S. Pat. No. 6,863,933 (Cramer et al.), U.S. Pat. No. 7,112,621(Rohrbaugh et al.), US 2003/148684 (Cramer et al.) and US 2005/008839(Cramer et al.).

The acquisition layer may be stabilized by a latex binder, for example astyrene-butadiene latex binder (SB latex). Processes for obtaining suchlatices are known, for example, from EP 149880 (Kwok) and US2003/0105190 (Diehl et al.). In certain embodiments, the binder may bepresent in the acquisition layer 52 in excess of about 12%, about 14% orabout 16% by weight. SB latex is available under the trade name GENFLO™3160 (OMNOVA Solutions Inc.; Akron, Ohio).

A distribution layer 54 may also be present. The function of adistribution layer is to spread the insulting fluid liquid over a largersurface within the article so that the absorbent capacity of the corecan be more efficiently used. Typically the distribution layer is madeof a nonwoven material based on synthetic or cellulosic fibers andhaving a relatively low density. The density of the distribution layermay vary depending on the compression of the article, but may typicallyrange from 0.03 to 0.25 g/cm³, in particular from 0.05 to 0.15 g/cm³measured at 0.30 psi (2.07 kPa). The distribution layer 54 may also be amaterial having a water retention value of from 25 to 60, preferablyfrom 30 to 45, measured as indicated in the procedure disclosed in U.S.Pat. No. 5,137,537. The distribution layer 54 may typically have anaverage basis weight of from 30 to 400 g/m², in particular from 100 to300 g/m². As shown in FIG. 2, the distribution layer may be roundedtowards the back of the article. The distribution layer may be alsoprofiled so that its basis weight towards the back of the article islower than towards the front.

The distribution layer may for example comprise at least 50% by weightof crosslinked cellulose fibers. The crosslinked cellulosic fibers maybe crimped, twisted, or curled, or a combination thereof includingcrimped, twisted, and curled. This type of material has been used in thepast in disposable diapers as part of an acquisition system, for exampleUS 2008/0312622 A1 (Hundorf). The crosslinked cellulosic fibers providehigher resilience and therefore higher resistance against thecompression in the product packaging or in use conditions, e.g. underbaby weight.

Fastening System

The absorbent article may include a fastening system. The fasteningsystem can be used to provide lateral tensions about the circumferenceof the absorbent article to hold the absorbent article on the wearer.This fastening system is not necessary for training pant article sincethe waist region of these articles is already bonded. The fasteningsystem usually comprises a fastener 42 such as tape tabs, hook and loopfastening components, interlocking fasteners such as tabs & slots,buckles, buttons, snaps, and/or hermaphroditic fastening components,although any other known fastening means are generally acceptable. Alanding zone is normally provided on the front waist region of thearticle for the fastener 42 to be releasably attached. Some exemplarysurface fastening systems are disclosed in U.S. Pat. No. 3,848,594, U.S.Pat. No. 4,662,875, U.S. Pat. No. 4,846,815, U.S. Pat. No. 4,894,060,U.S. Pat. No. 4,946,527, U.S. Pat. No. 5,151,092 and U.S. Pat. No.5,221,274 (Buell). An exemplary interlocking fastening system isdisclosed in U.S. Pat. No. 6,432,098. The fastening system may alsoprovide a means for holding the article in a disposal configuration asdisclosed in U.S. Pat. No. 4,963,140 (Robertson et al.)

The fastening system may also include primary and secondary fasteningsystems, as disclosed in U.S. Pat. No. 4,699,622 to reduce shifting ofoverlapped portions or to improve fit as disclosed in U.S. Pat. No.5,242,436, U.S. Pat. No. 5,499,978, U.S. Pat. No. 5,507,736, and U.S.Pat. No. 5,591,152.

Front and Back Ears 46, 40

The absorbent article may comprise front ears 46 and back ears 40 as isknown in the art. The ears can be integral part of the chassis, forexample formed from the topsheet and/or backsheet as side panel.Alternatively, as represented in FIG. 2, they may be separate elementsattached by gluing and/or heat embossing. The back ears 40 areadvantageously stretchable to facilitate the attachment of the tabs 42on the landing zone 44 and maintain the taped diapers in place aroundthe wearer's waist. The front ears 46 may also be elastic or extensibleto provide a more comfortable and contouring fit by initiallyconformably fitting the absorbent article to the wearer and sustainingthis fit throughout the time of wear well past when absorbent articlehas been loaded with exudates since the elasticized ears allow the sidesof the absorbent article to expand and contract.

Barrier Leg Cuffs 34 and Gasketing Cuffs 32

Absorbent articles such as diapers or training pants may typicallyfurther comprise components that improve the fit of the article aroundthe legs of the wearer, in particular barrier leg cuffs 34 and gasketingcuffs 32. The barrier leg cuffs 32 may be formed by a piece of material,typically a nonwoven, which is partially bonded to the rest of thearticle and can be partially raised away and thus stand up from theplane defined by the topsheet, when the article is pulled flat as shownfor example in FIG. 3. The barrier leg cuffs 34 can provide improvedcontainment of liquids and other body exudates approximately at thejunction of the torso and legs of the wearer. The barrier leg cuffs 34extend at least partially between the front edge and the back edge ofthe absorbent article on opposite sides of the longitudinal axis and areat least present adjacent to the crotch point (C) of the core.

The barrier leg cuffs 34 may be delimited by a proximal edge 64 joinedto the rest of the article, typically the topsheet and/or the backsheet,and a free terminal edge 66 intended to contact and form a seal with thewearer's skin. The barrier leg cuffs 34 may be joined at the proximaledge 64 with the chassis of the article by a bond 65 which may be madefor example by adhesive bonding, fusion bonding or combination of knownbonding means. The bond 65 at the proximal edge 64 may be continuous orintermittent.

The barrier leg cuffs 34 can be integral with (i.e. formed from) thetopsheet or the backsheet, or more typically be formed from a separatematerial joined to the rest of the article. Typically the material ofthe barrier leg cuffs may extend through the whole length of the articlebut is “tack bonded” to the topsheet towards the front edge and backedge of the article so that in these sections the barrier leg cuffmaterial remains flush with the topsheet. Each barrier leg cuff 34 maycomprise one, two or more elastic strings 35 close to this free terminaledge 66 to provide a better seal.

In addition to the barrier leg cuffs 34, the article may comprisegasketing cuffs 32, which are formed in the same plane as the chassis ofabsorbent article, in particular may be at least partially enclosedbetween the topsheet and the backsheet, and may be placed laterallyoutwardly relative to the barrier leg cuffs 34. The gasketing cuffs 32can provide a better seal around the thighs of the wearer. Usually eachgasketing leg cuff 32 will comprise one or more elastic string orelastic element 33 comprised in the chassis of the diaper for examplebetween the topsheet and backsheet in the area of the leg openings.

U.S. Pat. No. 3,860,003 describes a disposable diaper which provides acontractible leg opening having a side flap and one or more elasticmembers to provide an elasticized leg cuff (a gasketing cuff). U.S. Pat.No. 4,808,178 (Aziz) and U.S. Pat. No. 4,909,803 (Aziz) describedisposable diapers having “stand-up” elasticized flaps (barrier legcuffs) which improve the containment of the leg regions. U.S. Pat. No.4,695,278 (Lawson) and U.S. Pat. No. 4,795,454 (Dragoo) describedisposable diapers having dual cuffs, including gasketing cuffs andbarrier leg cuffs. All or a portion of the barrier leg and/or gasketingcuffs may be treated with a lotion.

Elastic Waist Feature

The absorbent article may also comprise at least one elastic waistfeature (not represented) that helps to provide improved fit andcontainment. The elastic waist feature is generally intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature preferably extends at least longitudinallyoutwardly from at least one waist edge of the absorbent core 28 andgenerally forms at least a portion of the back side of the absorbentarticle. Disposable diapers can be constructed so as to have two elasticwaist features, one positioned in the front waist region and onepositioned in the back waist region. The elastic waist feature may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. No. 4,515,595, U.S. Pat. No. 4,710,189, U.S. Pat.No. 5,151,092 and U.S. Pat. No. 5,221,274.

Relations Between the Layers and Components

Apart from the core-to-backsheet gluing pattern described in detailspreviously, adjacent layers may be joined together using conventionalbonding method such as adhesive coating via slot coating or spraying onthe whole or part of the surface of the layer, or thermo-bonding, orpressure bonding or combinations thereof. Most of the bonding betweencomponents is for clarity and readability not represented in the Figure.Bonding between the layers of the article should be considered to bepresent unless specifically excluded. Adhesives may be typically used toimprove the adhesion of the different layers, for example between thebacksheet and the core wrap. The adhesives used may be any standardhotmelt glue as known in the art.

Method of Making

Apart from the method for applying the gluing pattern described indetails previously, the absorbent article may be made otherwise by anyconventional methods known in the art. In particular the articles may behand-made or industrially produced at high speed on a modern convertingline.

Test Procedures

The values indicated herein are measured according to the methodsindicated herein below, unless specified otherwise. All measurements areperformed at 21° C.±2° C. and 50%±20% RH, unless specified otherwise.All samples should be kept at least 24 hours in these conditions toequilibrate before conducting the tests, unless indicated otherwise. Allmeasurements should be reproduced on at least 4 samples and the averagevalue obtained indicated, unless otherwise indicated.

Centrifuge Retention Capacity (CRC)

The CRC measures the liquid absorbed by the superabsorbent polymerparticles for free swelling in excess liquid. The CRC is measuredaccording to EDANA method WSP 241.2-05.

Dry Absorbent Core Caliper Test

This test may be used to measure the caliper of the absorbent core(before use i.e. without fluid loading) in a standardized manner.

Equipment: Mitutoyo manual caliper gauge with a resolution of 0.01 mm,or equivalent instrument.

Contact Foot: Flat circular foot with a diameter of 17.0 mm (±0.2 mm). Acircular weight may be applied to the foot (e.g., a weight with a slotto facilitate application around the instrument shaft) to achieve thetarget weight. The total weight of foot and added weight (includingshaft) is selected to provide 2.07 kPa (0.30 psi) of pressure to thesample.

The caliper gauge is mounted with the lower surface of the contact footin an horizontal plane so that the lower surface of the contact footcontacts the center of the flat horizontal upper surface of a base plateapproximately 20×25 cm. The gauge is set to read zero with the contactfoot resting on the base plate.

Ruler: Calibrated metal ruler graduated in mm.

Stopwatch: Accuracy 1 second.

Sample preparation: The core is conditioned at least 24 hours asindicated above.

Measurement procedure: The core is laid flat with the bottom side, i.e.the side intended to be placed towards the backsheet in the finishedarticle facing down. The point of measurement (e.g. the crotch point C)is carefully drawn on the top side of the core taking care not tocompress or deform the core.

The contact foot of the caliper gauge is raised and the core is placedflat on the base plate of the caliper gauge with the top side of thecore up so that when lowered, the center of the foot is on the markedmeasuring point.

The foot is gently lowered onto the article and released (ensurecalibration to “0” prior to the start of the measurement). The calipervalue is read to the nearest 0.01 mm, 10 seconds after the foot isreleased.

The procedure is repeated for each measuring point. If there is a foldat the measuring point, the measurement is done in the closest area tothis point but without any folds. Ten articles are measured in thismanner for a given product and the average caliper is calculated andreported with an accuracy of one tenth mm.

Absorbent Article Caliper Test

The Absorbent Article Caliper Test can be performed as for the DryAbsorbent Core Caliper Test with the difference that the caliper of thefinished absorbent article is measured instead of the caliper of thecore. The point of measurement may correspond vertically with the crotchpoint of the core as defined earlier. If the absorbent articles wereprovided folded and/or in a package, the articles to be measured areunfolded and/or removed from the center area of the package. If thepackage contains more than 4 articles, the outer most two articles oneach side of the package are not used in the testing. If the packagecontains more than 4 but fewer than 14 articles, then more than onepackage of articles is required to complete the testing. If the packagecontains 14 or more articles, then only one package of articles isrequired to perform the testing. If the package contains 4 or fewerarticles then all articles in the package are measured and multiplepackages are required to perform the measurement. Caliper readingsshould be taken 24±1 hours after the article is removed from thepackage, unfolded and conditioned. Physical manipulation of productshould be minimal and restricted only to necessary sample preparation.

Any elastic components of the article that prevent the article frombeing laid flat under the caliper foot are cut or removed. These mayinclude leg cuffs or waistbands. Pant-type articles are opened or cutalong the side seams as necessary. Apply sufficient tension to flattenout any folds/wrinkles Care is taken to avoid touching and/orcompressing the area of measurement.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An absorbent article for personal hygiene havinga wearer-facing side, a garment-facing side and a longitudinal axis, thearticle comprising: a topsheet on the wearer-facing side; a backsheet onthe garment-facing side; an absorbent core between the topsheet and thebacksheet, the absorbent core comprising: an absorbent materialcomprising a superabsorbent polymer; a core wrap enclosing the absorbentmaterial; a first channel disposed on one side of the longitudinal axisand a second channel disposed on the other side of the longitudinalaxis, and an area between the channels; wherein the absorbent core isattached to the backsheet at least by: a first glue, having a first glueapplication area and a first glue application pattern, wherein the firstglue application area is at least partially disposed in the area betweenthe channels; and a second glue, having a second glue application areaand a second glue application pattern, wherein the second glueapplication area is at least partially outside the area between thechannels, and wherein the first channel and second channel are at leastpartially not attached by the first glue and second glue to thebacksheet, and wherein the first glue application pattern differs fromthe second glue application pattern.
 2. The absorbent article accordingto claim 1 wherein the first glue application pattern is continuous. 3.The absorbent article according to claim 2, wherein the first glue isslot-coated.
 4. The absorbent article according to claim 1, wherein thesecond glue application pattern is discontinuous.
 5. The absorbentarticle according to claim 4, wherein the second glue applicationpattern is at least one of a plurality of large swirls, a plurality ofmini-swirls or randomly deposited adhesive fibers.
 6. The absorbentarticle according to claim 1, wherein the second glue application areais larger than the first glue application area.
 7. The absorbent articleaccording to claim 6, wherein the second glue application area is atleast 3 times larger than the first glue application area.
 8. Theabsorbent article according to claim 1, wherein the second glueapplication area comprises at least a first portion on one side oflongitudinal axis and at least a second portion on the other side of thelongitudinal axis, and both portions extend along the full length of theabsorbent core.
 9. The absorbent article according to claim 8, whereinthe first and second portion of the second glue application area extendalong the full length of the backsheet.
 10. The absorbent articleaccording to claim 8, wherein the absorbent core has a first and asecond longitudinally extending side edges, and the longitudinallyextending first portion is at least partially present between the firstlongitudinally extending side edge and the first channel, and thelongitudinally extending second portion is at least partially presentbetween the second longitudinally extending side edge of the core andthe second channel.
 11. The absorbent article according to claim 1,wherein the absorbent core has a front edge and a back edge, and saidfront and back edges are attached along their entire widths by a frontportion and a back portion of the second glue application arearespectively.
 12. The absorbent article according to claim 1, whereinthe second glue application area approximately has a roman II numeralshape.
 13. The absorbent article according to claim 1, wherein theabsorbent material of the absorbent core comprises less than 20% ofcellulosic fibers, by weight of the absorbent material.
 14. Theabsorbent article according to claim 13, wherein the absorbent materialis free of cellulosic fibers.
 15. The absorbent article according toclaim 1 wherein the channels are areas substantially free of absorbentmaterial which are surrounded by absorbent material.
 16. The absorbentarticle according to claim 1, wherein a top side and a bottom side ofthe core wrap are attached to each other through the channels.
 17. Theabsorbent article according to claim 1, wherein the first channel andthe second channel are longitudinally extending and each have a lengthas projected on the longitudinal axis which is at least 25% of thelength of the absorbent core.
 18. A process for gluing an absorbent coreto a backsheet, the process comprising the steps of: providing anabsorbent core having a longitudinal axis and comprising: an absorbentmaterial comprising a superabsorbent polymer; a core wrap enclosing theabsorbent material; a first channel disposed on one side of thelongitudinal axis and a second channel disposed on the other side of thelongitudinal axis; applying a first glue on the backsheet or theabsorbent core, on a first glue application area according to a firstglue application pattern; applying a second glue on the backsheet or theabsorbent core, on a second glue application area according to a secondglue application pattern; then bringing the backsheet and the absorbentcore in contact so that they are attached by the first glue and secondglue.
 19. A process according to claim 18, wherein the first glue isapplied with a contact applicator, and/or the second glue is applied bya non-contact applicator.
 20. A process according to claim 18, whereinthe second glue is applied by a plurality of nozzles disposed inparallel, wherein for each core/backsheet combination, at least some ofthe nozzles are turned on and off during the application of the secondglue to provide a second glue application area comprising longitudinallyextending portions of different lengths.